X-ray tubes with a rotary anode are used in different X-ray systems, for example in a CT-system. For the generation of X-rays, the anode is rotated inside the tube. Prior to the assembly of the tube, a static balancing is achieved, for example, by cutting away materials from rotatable components. Although statically balanced, during operation thermo-mechanical and material ageing effects may cause a distortion of the state of balance of an X-ray tube's anode and, for example, the X-ray tube's rotor as well. In some cases this might go beyond acceptable levels so that the tube has to be replaced. Furthermore, as an example, in a CT-system, an X-ray tube is rotating about the patient and generates a fan beam of X-rays. Opposite and with it on a gantry rotates a detector system which converts the attenuated X-rays to electrical signals. Then, a computer system reconstructs an image of the patient's body in the region of interest. The imbalance of the anode may cause severe vibration of the tube housing assembly and thus malfunction of the detectors resulting in low image data quality. The imbalance may further cause reduction of bearing life and also an increase of acoustic noise. Usually, prior to mounting them into X-ray tubes, anode rotors will be assembled, then tested for vibration and balanced by drilling or cutting away material at the proper locations. After this, no further balancing is possible, as the rotors are enclosed in vacuum-tight tube frames.